Control valves used for supplying cryogenically liquified fuel to larger rocket engines must operate under extreme operating conditions. For example, they must operate at extremely low temperature and are subject to high mass flow and high pressure. Furthermore, the switching times for opening and closing the valve must be short and the energy requirements low. The effects of such operating conditions must be taken into consideration in the design and construction of such control valves.
Control valves for use with cryogenically liquefied rocket fuel are known in which the switching forces required for opening and closing the valve are essentially determined by flow resistance or interference forces that act on the valve plunger and other movable valve components, especially as the valve plunger is being moved to open or close the valve. With these known types of control valves, the flow forces are not reduced or compensated by the structural design of the valves, and therefore such forces undesirably increase the drive power required for opening or closing the valve, particularly when large nominal dimensions, high nominal pressures, and short switching times are required.